1. Field of Invention
This invention generally relates to seat belt restraint systems. More specifically, this invention relates to seat belt restraint systems for both adults and children.
2. Prior Art
Vehicle occupant restraints, including seat belt devices and systems, are important and well-known components of vehicle safety systems. When a vehicle experiences severe impact, a properly belted-in occupant is held in place by the webbing, thereby avoiding many serious, if not fatal, physical collisions with vehicle interior and/or being thrown from the vehicle. Since their introduction seat belts have saved countless lives and reduced the severity of injury in countless more.
Three-point seat belt systems are widely used and well known. There are three fixation points on the seat belt webbing. The upper end of the shoulder belt is extendable and retractable to the upper portion of the vehicle adjacent the shoulder of an occupant of normal size, providing the first fixation point. The lower end of the shoulder belt extends to a lap belt via a sliding seat belt latch. One end of the lap belt is continuously connected to the lower end of the shoulder belt. The other end is anchored to the vehicle and disposed on the outboard side of the occupant, resulting in the second fixation point. The seat belt latch has a webbing loop, through which the lap belt is threaded, such that the seat belt latch is slidable along the lap belt, and a tongue plate engageable with a seat belt buckle. The seat belt buckle is anchored to the vehicle and disposed on the inboard side of the occupant, generating the third fixation point. Three-point seat belt restraint systems improve the performance of occupant restraint over two-point seat belt restraint systems by restricting both the occupant's upper and lower body motions.
Many patents have been issued to three-point seat belt restraint systems. However, existing three-point seat belt restraint systems have an important drawback when used by a child or a person of small stature. The shoulder belt would run across the child's head, neck, or above. Some children have placed the shoulder belt behind their back. Obviously, this position diminishes any benefit that could be derived from the shoulder belt. Even worse, in vehicles equipped with an airbag, the child, who is not restrained or who is improperly restrained, is potentially an out-of-position occupant.
Children have used booster chairs. However, customers incur added costs in buying booster chairs. Booster chairs also add weight to vehicles. On the other hand, when children grow bigger, they are getting reluctant to sit in booster chairs. As a result, some children either simply do not wear a seat belt or just wear a lap belt. Some patents have been issued in designing seat belt restraint systems or devices for children.
U.S. Pat. No. 5,609,367, issued to Eusebi et al., on Mar. 11, 1997, describes a device for adjusting the height of the web guide to change the departure angle of the shoulder belt from the restraint point across a seated child. A second web guide is mounted on a vertically movable height adjuster. The second web guide has an open slot to receive the shoulder belt.
Although the device can effectively adjust the departure angle of the shoulder belt across the seated child and improve the comfort and safety performance for children, it might incur too big added cost in manufacturing, because making a vertically movable height adjuster with desired strength for vehicle safety on the lower B-pillar or on the side of vehicle seat is going to be costly. The space in between the vehicle seat and the B-pillar is very limited. A web guide mounted on a height adjuster would take out even more space. Also, the proposed device is using the same attachment space as the seat mounted side impact airbag. Therefore, it may not be used in the vehicles equipped with side impact airbags. Side impact airbags have become standard safety components for many vehicles in recent years.
U.S. Pat. No. 5,335,957, issued to Golder, on Aug. 9, 1994, describes a device having a tubular passageway for receiving and engaging portions of both the shoulder and the lap belt.
This device restricts the angle between the shoulder belt and the lap belt thereby avoiding the interference between the shoulder belt and the child's head and improving the comfort of wearing the seat belt restraint system, However, if the tubular passageway is made shorter for convenience of carrying, the shoulder belt would be very close to the child's head and will slap onto the child's head in a vehicle accident. On the other hand, if the tubular passageway is made longer for safety concern, it is going to be too large to carry around. Further more, in a vehicle accident when the shoulder belt is in tension, the tubular passageway would naturally be forced to slide inboard and the angle between the shoulder belt and the lap belt would become bigger, thereby diminishing the effectiveness of this device. Most important of all, when this device receives and engages portions of both the shoulder and lap belts in keeping the shoulder belt away from the seated child's head, it lifts up the lap belt. This will increase the risk of occupant “submarine”, that's occupant sliding under the lap belt.
There are some other add-on products on the market. Unfortunately, these products are primarily for comfort instead of for safety.
Therefore, it remains desirable to provide a seat belt restraint system that is safer, more comfortable and convenient to use, and simpler and less expensive to manufacture, for children or people of small stature.